In a conventional semiconductor laser, an oscillation wavelength is changed in accordance with the energy band gap in an active region by controlling temperature thereof. In other words, the energy band gap in an active region is controlled depending upon the temperature thereof. Accordingly, a semiconductor laser can be applied to the several uses requiring different oscillation wavelengths respectively in the field of an optical communication system, an optical information processing system etc. For the adoption of such a semiconductor laser in the systems mentioned above, the size thereof can be smaller and the consuming power therein can be reduced.
According to the semiconductor laser in which the temperature thereof is controlled, however, the range of an oscillation wavelength is controlled as wide as several ten .ANG. and a maximum response rate thereof is not so high as expected in a specific use.
In addition to the semiconductor laser mentioned above, there has been proposed a semiconductor laser in which an oscillation wavelength is changed by controlling the Bragg wavelength as described on pages 63 to 65 of "ELECTRONICS LETTERS Jan. 17th 1985 Vol. 21 No. 2".
According to the semiconductor laser described therein, however, an oscillation wavelength is changed in accordance with the refractive index of lattice so that the range to be changed is not so wide as expected.